A Brooklyn teacher fired for posting “repulsive’’ Facebook comments suggesting her misbehaving students should drown now faces only a two-year suspension without pay.

That’s the “lesser penalty” decided on by Department of Education arbitrator Randi Lowitt, The Post has learned.

Lowitt first ruled in June 2011 that Christine Rubino, a veteran teacher at PS 203 in Flatbush, should be fired for ranting on Facebook, “I’m thinking the beach sounds like a wonderful idea for my 5th graders. I HATE THEIR GUTS! They are all the devils spawn!”

The comment came a day after a 12-year-old Harlem girl, Nicole Suriel, drowned on a school trip to a Long Island beach.

While “offensive” and “repulsive,” Jaffe concluded, Rubino’s remarks were made outside the school building, after hours, and were only circulated among adult Facebook friends.

Jaffe found no evidence that Rubino meant the kids any actual harm or that her outburst “affected her ability to teach” — and sent the matter back to Lowitt.

Lowitt rejected the teacher’s request for back pay and to return to her classroom in the fall. And she insisted on the suspension, citing her finding that Rubino tried to save herself by getting a friend to claim authorship of the comments. The friend later admitted lying to probers, but Rubino denied putting her up to it.

Lowitt ruled in her second opinion that Rubino was guilty not only of conduct unbecoming a teacher but “lying and obfuscation.”

“The [suspension] penalty is based on the lie, the continued lie, and the inability to acknowledge the lie,” Lowitt wrote.

Rubino plans to appeal, saying she has “suffered enough.” A two-year suspension without pay comes to a loss of $150,000.